For the first time, sources of carbon dioxide in Salt Lake County can be accurately estimated at the level of individual buildings and roads and by hour of the day. Building on this capability, emissions of toxic air pollutants ...

States will gain large, widespread, and nearly immediate health benefits if EPA sets strong standards in the final Clean Power Plan, according to the first independent, peer-reviewed paper of its kind, published today in ...

Emissions linked to hydraulic fracturing, the method of drilling for natural gas commonly known as "fracking," can be detected hundreds of miles away in states that that forbid or strictly control the practice, according ...

Alberta's oilsands have been the subject of controversy and discussion for many years. But residents in the Athabasca oilsands region needn't hold their breath about air pollution, says a professor in the University of Alberta's ...

NASA researchers, working in concert with the Air Force Research Laboratory (AFRL) and FlexSys Inc., of Ann Arbor, Michigan, successfully completed initial flight tests of a new morphing wing technology that has the potential ...

The continual increase in global incomes means people are living more comfortably, including having the ability to afford air conditioning. Staying cool is good but there's a wealth of fallout. The demand for more "AC" will ...

The Calbuco volcano, a 2,000 metre peak in southern Chile, sent a column of ash about 15km skywards twice on the night of April 22 and early the following morning. As the risk of deadly flows of ash and hot air was immediate, ...

UK-based Williams Advanced Engineering, the technology and engineering services business of the Williams Group, has collaborated with UK-based Aerofoil Energy to develop an aerodynamic device that can reduce the energy consumed ...

Earth's atmosphere

The Earth's atmosphere is a layer of gases surrounding the planet Earth that is retained by the Earth's gravity. It has a mass of about five quadrillion metric tons. Dry air contains roughly (by volume) 78.08% nitrogen, 20.95% oxygen, 0.93% argon, 0.038% carbon dioxide, and trace amounts of other gases. Air also contains a variable amount of water vapor, on average around 1%. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention (greenhouse effect), and reducing temperature extremes between day and night.

There is no definite boundary between the atmosphere and outer space. It slowly becomes thinner and fades into space. An altitude of 120 km (75 mi) marks the boundary where atmospheric effects become noticeable during atmospheric reentry. The Kármán line, at 100 km (62 mi), is also frequently regarded as the boundary between atmosphere and outer space. Three quarters of the atmosphere's mass is within 11 km (6.8 mi; 36,000 ft) of the surface.